Extrogenic hormones coordinate a variety of physiological responses that are essential for reproduction. In mammals, including humans, the uterus and the pituitary gland contain estrogen responsive cells that are the subject of the proposed studies. On the basis of recent investigations estrogen receptors appear to be nuclear proteins probably bound to other nuclear constituents with or without the estrogenic ligand. This proposal details studies using aqueous two-phase partitioning to examine the changes in structure of the receptor upon binding estrogenic compounds, and to provide some insight into the thermodynamics of such changes. Development of minichromosome systems using viral vectors will provide a means to isolate and amplify specific gene sequences and their accompanying chromatin proteins. This is particularly important because current data suggests that nucleotide sequence of DNA or nuclear proteins alone do not provide the specificity required to explain the complex action of estrogens. Receptor concentration is also essential to the physiological response to estrogen. Studies will be carried out to assess the biological regulation of development of estrogen receptors in the uterus and pituitary. One of the manifestations of estrogen responsiveness is the growth of responsive tissues. Two approaches will be used to find genes involved in growth that are regulated by estrogen. the protooncogenes are genes that appear to be related intimately to growth and development. Cloned probes for these genes are available and can be used to determine if and how these genes are related to estrogen regulated growth. A second approach will be to use cDNA libraries made from estrogen stimulated and control tissues of rats that differ in their growth response to estrogens. This also may provide a means for identifying growth essential genes that respond to estrogenic hormones. If either of these methods identifies an estrogen responsive gene, it will be used for studies on chromatin interaction with estrogen receptor.